package com.hmdp.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

	@Resource
	private RedisIdWorker redisIdWorker;

	@Resource
	private ISeckillVoucherService seckillVoucherService;

	@Resource
	private StringRedisTemplate stringRedisTemplate;

	@Resource
	private RedissonClient redissonClient;

	private static final DefaultRedisScript<Long> SECKILL_SCRIPT;//创建一个脚本

	//这里的静态代码库作用是项目一运行就加载这个lua脚本文件，提高性能
	static {
		SECKILL_SCRIPT = new DefaultRedisScript<>();//创建一个脚本
		SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));//选择你脚本所在的位置
		SECKILL_SCRIPT.setResultType(Long.class);//设置返回类型
	}

	//这是一个阻塞队列
	private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
	//创建线程池
	private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

	@PostConstruct//在当前类初始化完毕之后立即执行这个方法内部的代码
	public void init() {
		//向线程池里添加要执行的任务
		SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
	}

	//创建线程任务
	private class VoucherOrderHandler implements Runnable {
		/**
		 * 线程任务
		 */
		@Override
		public void run() {
			while (true) {
				try {
					//1.获取队列中的订单信息
					VoucherOrder voucherOrder = orderTasks.take();
					//2.创建订单
					handleVoucherOrder(voucherOrder);
				} catch (InterruptedException e) {
					log.error("处理订单异常");
				}
			}
		}
	}

	private void handleVoucherOrder(VoucherOrder voucherOrder) {
		//1.获取用户
		Long userId = voucherOrder.getUserId();
		// 2.创建锁对象
		RLock lock = redissonClient.getLock("lock:order:" + userId);
		// 3.尝试获取锁
		boolean isLock = lock.tryLock();
		// 4.判断是否获得锁成功
		if (!isLock) {
			// 获取锁失败，直接返回失败或者重试
			log.error("不允许重复下单！");
			return;
		}
		try {
			//注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
			proxy.createVoucherOrder(voucherOrder);
		} finally {
			// 释放锁
			lock.unlock();
		}
	}

	//成员变量，在seckillVoucher方法中初始化，放在成员变量位置是为了让当前类共享
	private IVoucherOrderService proxy;

	//优化改造：基于Lua脚本实现对优惠券库存和是否已有订单进行判断
	@Override
	public Result seckillVoucher(Long voucherId) {
		//获取用户
		Long userId = UserHolder.getUser().getId();
		long orderId = redisIdWorker.nextId("order");
		// 1.执行lua脚本
		Long result = stringRedisTemplate.execute(
				SECKILL_SCRIPT,
				Collections.emptyList(),
				voucherId.toString(), userId.toString(), String.valueOf(orderId)
		);
		int r = result.intValue();
		// 2.判断结果是否为0
		if (r != 0) {
			// 2.1.不为0 ，代表没有购买资格
			return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
		}
		//2.2返回值为0，有购买资格，把下单信息保存到阻塞队列中去
		VoucherOrder voucherOrder = new VoucherOrder();
		// 2.3.订单id
		orderId = redisIdWorker.nextId("order");
		voucherOrder.setId(orderId);
		// 2.4.用户id
		voucherOrder.setUserId(userId);
		// 2.5.代金券id
		voucherOrder.setVoucherId(voucherId);
		//2.6 放入阻塞队列
		orderTasks.add(voucherOrder);
		//3.获取代理对象
		proxy = (IVoucherOrderService) AopContext.currentProxy();
		//4.返回订单id
		return Result.ok(orderId);
	}


	/*@Override
	public Result seckillVoucher(Long voucherId) {
		// 1.查询优惠券
		SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
		// 2.判断秒杀是否开始
		if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
			// 尚未开始
			return Result.fail("秒杀尚未开始！");
		}
		// 3.判断秒杀是否已经结束
		if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
			// 尚未开始
			return Result.fail("秒杀已经结束！");
		}
		// 4.判断库存是否充足
		if (voucher.getStock() < 1) {
			// 库存不足
			return Result.fail("库存不足！");
		}
		Long userId = UserHolder.getUser().getId();

		//创建锁对象
		//SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
		RLock lock = redissonClient.getLock("lock:order:" + userId);

		//获取锁对象
		boolean isLock = lock.tryLock();
		//加锁失败
		if (!isLock) {
			//获取锁失败,返回错误信息或者重试
			return Result.fail("不允许重复下单");
		}
		try {
			//获取代理对象(事务)
			IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
			return proxy.createVoucherOrder(voucherId);
		} finally {
			//释放锁
			lock.unlock();
		}
	}*/

	@Transactional
	public void createVoucherOrder(VoucherOrder voucherOrder) {
		//一人一单
		Long userId = UserHolder.getUser().getId();

		synchronized (userId.toString().intern()) {
			// 5.1.查询订单
			int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
			// 5.2.判断是否存在
			if (count > 0) {
				// 用户已经购买过了
				log.info("用户已经购买过了");
				return;
			}

			// 6.扣减库存
			boolean success = seckillVoucherService.update()
					.setSql("stock = stock - 1") // set stock = stock - 1
					.eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0) // where id = ? and stock > 0
					.update();
			if (!success) {
				// 扣减失败
				log.info("库存不足");
				return;
			}

			// 7.创建订单
			save(voucherOrder);
		}
	}
}
